Double-walled vacuum receptacle



March 20, 1928.

M. P. WETMORE DOUBLE-WALLED VACUUM REGEPTACLE Filed Jan. L, 1927.

- INVENTOR Miner P fl eimor'e ATTORNEY Patented Mar. 20, 1928.

'um'rsn STAT PATENT orr ics.

MINER I. WETMORE, OF NORWICH, CONNECTICUT, ASSTGNOR TO THE AMERICAN THERMOS BOTTLE ooivrrAivv, OF OHIO.

noRwIcrI, o'olvnn'otrronr, A CORPORATION OF DOUBLE-WALLEIQY vacuum. naonr'motn' I Application filed January 4, 1927. Serial. No. 158,856.

My invention relates to heat-insulating'receptacles of the so-called double-walled vacuum type, in which two cylinders are arranged concentrically to provide an annular vacuum chamber. These two cylinders, which are usually of thin glass, are united at the top to form the filler of the receptacle. The. inner cylinder constitutes a container tor liquids or solids. Since these glass cylin}. ders are easily breakable, it is necessary to provide spacing means in the vacuum chamber at or near the lower end of the inner container, sothat the latter may beprotectecl against jars or shocks. In the finished article, the walls of the vacuum chamber are silvered and the filler is housed in a suitable outer casing.

Heretotor'e the most common form of spacingmeans for the two cylindershasconsisted of small pads or disks of asbestos, which is heat-insulating. These asbestos spacing pads, which have. been in use for many years, are highly objectionable for several reasons. In the first place, these pads possess so-little elasticity that, when they are pushed in place between the two. cylinders, the tight fit that is required often results in breakage of the filler. The width of the annular chamber between the cylinders necessarily variesv in different fillers, and so it is diflicult to fitthe. pads properly into position in each chamber. Another objection to the old spacing pads is that, after the walls of the vacuum chamber have been silvered, the pads appear as round spots on the inner containers, because they prevent the silvering solution from coming in contact with the surface of the container. The most serious objection to the asbestos pads is due to the fact that they retain considerable moisture ,afterthe silvering operation, and it is impossible to. extract that moisture completely during the. subsequent vacuum-forming operation. This moisture-retaining property of the asbestos pads has always made the exhaustion of fillers a difficult operatiom requiring considerable. time and sometimes making it necessary to stop the vacuum pumps in order to remove the moisture that has. been drawn out of the pads, The presence of moisture and air in the asbestos pads, even in small amounts, will cause the vacuum to deteriorate and thereby impair the heat-- insulating qualities of the bottle. a

In order to overcome the foregoing and other objections and disadvantages of the old, asbestos spacing pads in vacuum receptacles, I have invented a new spacing means for the cylinders in the annular vacuum chamber. Briefly stated, the spacing means of my invention consists of an open circular spring of metal mounted under tension in the vacuum chamber and so shaped as to engage .both cylinders. An. easy way to form tl is sp ring is to corrugate a pie-ceofistraight spring wire and cut t-hiswire. intosections of the desired length. The spacing spring is formed by simply bending each corrugated wire section until it fits into the annu lar chamber betweenv the cylinders. The open or disconnected ends of .the annular spring cause the contact pointsto adjust themselves automatically when the spring. is nse te a 0 1 t ac psnt a Spacing spring fits properly in each filler, irrespective. of variations or. irregularities in the size of the vacuum chamber. Thesesprings are not only cheap to, ma -nutactuIrev andv easily put in place, but they retain; practically. no moisture and thereby facilitate the operation of producing the required vacuum in the filler. By coating the spring with nickel or othen silvery looking metal, the contact points, otthe spring with the cylinders are practically invisible after. the silvering operation. I

The practical. advantages of my invention will be more fully understood from a dc tailed description of the accompanying .drawingsin whlchl have illustrated twoembodiments of my invention. In these drawmgs' Fig.

mately on line 1 1 o fFig.

Fig. 2 is a transverse cross-section on line ,22 of Fig. l, showing the form arportions ofthe outer and inner cylinders;

and

Fig. 4c is a transverse cross-section on. l ne In 'Figs land 2 there isan outer cylinder 10. and an innercylinder 12 united at the top to form a filler. for vacuum receptacles.

1 represents. a double-walled glass 7 filler in longitudinal cross-section, approxicylinder orcontainer 12 againstbreakage, I provide a circular spac ng spring or ring 14 I of metal. -The construction of this ring is shown in Fig. 2. In itsggeneral shape orcontour, the ring 14 is in the form of a poly onal having sides 15 and corners 16. The

corners 16 arerounded humps which engage the outer'cylinder 10, while the sides 15 en gage the inner cylinder 12 at the points or contact areas 17. When I speak of contact points between the spring'a'nd cyl1nders,' I do'not use'the term in its strict mathematb cal sense, but in'itspractical meaning of a Fig. 2.

practical shape.

contact 'spot'or place of indefinite area.

The'spacing ring 14 is-madetrom cor rugated springwire, which may be round, or aflatribbon as shown, or of any other I At the present time I make by -corrugatinga continuous these rlngs length of springwire to providethe humps 16. The corrugated wire is cut into pieces ofthe required length, depending upon the diameterof the filler,,, and'these pieces of corrugatedwire are then bent into circular shape for insertion into the annular cham-' ber of the filler. The ends of the bent wire are free .or disconnected, as indicated at 18 in When the ring 14 is bent round for insertion in the vacuum ch'amber,it is placed under tension and theconta'ct points of the tensioned ring automatically adjust themselves against the. sides of the containers, irrespective of variations in sizeof the vacuum chambers of diflferent fillers. This automatic adjustment of the contact points is due to the fact that. the spacing'ring is open, by which Imean thatthe ends are not rigidly connected together. In the construction of Figs. 3 and 4,1 employ' two circular spacing springs or rings 19 connected at 20 and arranged in planes parallel with the axis of the filler. The

' rings 19, like the ring 14, are made of corrugated spring wire bent into polygonal i shape to provide humps 21 for engaging the outer cylinder 10 and sides 22 for engaging the inner cylinder 12. Vhat has been said plies to spacing rings 19fwithout the need of repetition. Atthe present time I preferto arrange my new spacing ring in a plane at right angles to the axis of the filler as shown from the preceding descriptionthat' my new spacing ring is of be carried out more efiiciently and in'less time than was possible with the-use of the forms than old. asbestospads, and finally results in a neater looking 'productj WVhen heat is used in the operations on the glass fillers after the insertionof the spacing rings, the metal from which these rlngs are made is heattreated, sothat the high' temperature to which the filler -is subsequentlysubjected will not take the elasticity out of the spacingspring, or at least not seriously affect it.

Although I have shown and described two specific constructions, I want it understood that my invention is not limited to the exact rounded humps suitably spaced and ar ranged to engage only the out-er cylinder, said ri'ngbeing soshaped" that the inner cylinder isengaged only by those portions of the ring that are intermediate said humps, whereby said ring when inserted under tension" into the space between said'cylinders automatically adjusts itself'into contact with both cylinders 2. As a means for spacing the inner and outer cylindersof a double-walled vacuum receptacle, an open ring bent intoshape from a straight piece, of spring wire and formed with outwardly extending humps suitably spaced and 'arrangedto engage only-the outer cylinder, those portions of the ring between said humps being adaptedto engage only the inner cylinder. J

3. As a newarticle of'manufacture for use in vacuum receptacles having outer and inner glass cylinders spaced to provide an annular vacuum chamber, a spacing member for said cylinders in said chamber consist'ing of an'op'en ring bent into shape from a straight piece of spring band or ribbon which is formed with outwardly extending humps suitably spaced and arranged to engage onlythe outer cylinder, those portions of, the ring between said humps being adaptabout the advantages of spacing ring 14 ap- 6 ed to engage only the innercylinder, said metal. ring being heat-treatedso that the heat used'in the operations on said glass cylinders will not substantially afiect the elasticity of said ring. i i

7 4.;In a double-walled vacuum receptacle having inner and outer cylinders spaced to form anflannular vacuum chamber, a spacmg member for" said cylinders'in said vacuumchambercomprising a strip of spring one-piece-open ring of. spring 7 metalbent to engage only the outer cylinder 'atYcertai'n points and'to engage only the inner cylinder at points which-are substantially intermediate the contact points of the outer cylinder, whereby said strip is in yield a able engagement with said cylinders, said strip being under tension in said chamber and its ends being free so that the engaging portions of the strip automatically adjust themselves into contact With the cylinders.

5. A double-Walled vacuum receptacle comprising an'inner and outer cylinder, said cylinders being spaced to provide an annular vacuum chamber, a. metal spacing spring mounted under tension in said chamber to space said cylinders, said spring being in the form of a polygon With free ends and so shaped that the corners of thepolygon engage only the outer cylinder and the sides of the polygon engage only the inner cylinder, whereby said spring is in yieldable engagement with both cylinders.

6. A double-Walled vacuum receptacle comprising an inner and outer cylinder, said cylinders being spaced to provide an annular vacuum chamber, and a tensioned metal spring bent to fit in said chamber and provided with a series of integral humps engaging only the outer cylinder, the spring sections between said humps engaging only the IHIIGI cylinder, said bent metal spring having free or open ends whereby the engaging portions of the spring automatically adjust themselves into contact With the cylinders irrespective of variations in the said chamber and corrugated to provide a series of outwardly extending bends engaging only the outer cylinder and a series of lnwa-rdly extending bends engagmg only the inner cylinder, the inner bends being radial- 1y displacedrelatively to the outer bends,

so that the open ends of said circular spring cause said outer and inner bends to adjust themselves automatically into contact With the cylinder When the spring is inserted into I said chamber,

MINER P. VVETMORE. 

